Need a second opinion,... or a second set of arms to...
 

...help throw this machine out my studio window!

The belligerent patient: A White Rotary circa 1920s-ish

Symptoms noted upon arrival at the hospital: Untimed - seriously untimed - like 125 degrees off. Feed dogs feeding roughly backwards. Hadn't sewn in years.

Patient property consigned at check in: Machine, one bobbin case, one bobbin - slightly out of round but better than many I've successfully used in other machines... (I have no spares either)

Treatment: Retimed all of it - the hook, the needlebar, the feed dogs. Re-centered the needlebar, Checked and reset "play" in the hook shaft, smoothed a couple of burrs on the hook.

Response to treatment: Timing looks great but might be a smidge off, skips one stitch in about 50 - could be tension, it's still a little tight both top and bottom for my liking. Fabric feeds beautifully. Sews along just great with tensioners both cleaned and all tension adjustments made until CRUNCH! Needle hits the hook and shatters.

Prognosis: Cruisin for a Bruisin!!

Seriously - I was test sewing - not a single skipped stitch in minutes worth of sewing then suddenly - as DH was coming down the stairs to check on my progress and I was all ready to tell him after 2 days of fighting that I'd finally conquered it - the needle shattered as it hit the hook.

I wasn't pulling the fabric, I wasn't pushing the fabric, I was guiding with one finger - crookedly, admittedly because the other hand was manually cranking the handwheel.

This happens "consistently" every once in a long while. By consistently, I mean I haven't finished more than 3 test sews in a row without it happening. Each time, I've caught it in time without breaking the needle but replacing it each time it thumped into the hook - except the last time when I shattered the needle because I was so sure it was fixed. This has clearly been an ongoing problem with this machine - based on needle strikes on the hook and a filed area right beside the strikes that effectively widens the slot for the needle.

All strikes are to the left side of the beginning of the slot preceding the hook tip - ie it appears some sort of deflection of the needle to the left (or the hook moving to the right?) right as the needle reaches the level of the hook and is supposed to enter the slot rather than giving me a heart attack with the smashed needle (that's a deep seated psychosis thanks to an early temperamental machine. ;))

Of course now I'm doubting some measurements.

1. I've tried timing at the 3/32" (2.5mm), also at the point where the needle thread loop is the biggest. Is there anyone out there who can take a measurement for me and tell me what their working White Rotary is set to? (I'll provide illustrated instructions to help check if needed!)
2. How much play do you have in the hook shaft? I set it to something similar to a Singer machine but of course this is a different beast. The turning backward thing continues to mess me up while test sewing and checking settings.

Any other things to check that I've missed? (I'm sure I've done more but I can't recall them at this point.)

I would check:

Hook mount to shaft
Hook Shaft play
Check immediately after crash (sounds almost like something is stiff when cold and loose when warm)

Thanks Steve!

The hook shaft play seems reasonable but I'm basing that on a Singer. I'll check it again. I do notice that moving the hook shaft to both "extremes" of its play doesn't seem to affect the hook's positioning but maybe it's just that minute.

The hook mount is a heck of an idea! I haven't seen the set screws for it - which might be why I didn't think of it - but I will look harder momentarily.

I think I was working my way to a scenario where something had to change tolerances as the sewing went on, but I hadn't thought "warmth" would be an issue in something so loose.

I will test and report back!

I've been up to my eyeballs in Corvair research, troubleshooting, cleaning, etc... It is a pleasure to "think sewing machine" for a bit!! Ya got me curious now.

Good luck I had a 1020 Sears that would do that all the time even after seeing several repair people. I just wanted to blow it up. Instead I got rid of it and got a Pfaff. So no help from me.

Oh!! Oh, I got it! :) Thanks to SteveH's suggestions!

The problem was staring me in the face the whole time but I kept discounting it as just an oddity of the machine.

There are no set screws to join the hook to the shaft. It looks like a pressed on bushing or something. That whole bushing had slid back, orienting the hook too far to the right. This is why I typically don't remove old oil until I'm finished servicing! I could see exactly where it belonged and how far it had shifted.

[ATTACH=CONFIG]525952[/ATTACH]

It was far enough left that it sewed most of the time, but something - possibly vibration or temperature caused it to shift a tiny bit to the right and Crunch!

Now that it's adjusted, the clearance between hook and needle is better and the 1/50 skipped stitches are also gone.

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I saw that clue a number of times too - the loop would sometimes form but not be far enough to the right to get grabbed by the hook. I ignored way too much here. I'll blame mild burn out for that at this time.:(

I completely know the feeling you're talking about. I think I literally saw red a few times with this one! I felt the blood pressure spikes! It's funny, the Sears machines of that vintage (of most vintages actually) are usually quite well built. If it was just one or two technicians, I'd think maybe one wanted to sell you a new machine and one just didn't know, but several.... ugh.

This White suffered some pretty good abuse at some point - I still can't figure out the forensics of how the hook shaft got turned so far and the race was pushed back so far. There are a number of screws that were loose / mangled, so it's possible Bubba was here before me.

Who?

CD in Oklahoma

Don't beat yourself up. That problem was there a long time and no one else found it before you. You mentioned filed areas trying to increase the clearances to solve the problem that way. It probably helped just enough to make them think they had found and fixed at least most of the problem.
Rodney

Uh Bubba and/or Sweet Thang? ;)

It was a fairly aggressive file too. I don't know why it didn't clue me in that the needle was so close to that side all the time. I think perhaps I just got too close to it by that time.

In 3 days of fairly solid fighting, I did NOT bond with that machine at all! Too many things seemed needlessly complex for the sake of... probably patents or avoiding patents? The top tensioner kept snapping my thread as I was trying to thread the machine because of a really bizarre design (and Aurifil thread which is thin to begin with), the pins to "hold" the hook seemed entirely unnecessary and in fact are on most other class 15 type machines (though this is more like a 115 - rotary and all...), the bobbin case is fiddly, and that needlebar hitting the foot if the foot is up when trying to bring the bobbin thread up or checking things like timing made me consider trying to heave it out the window that's at eye height in my studio.

Only the fear of not quite making it and having it come back at me stopped me. ;) I wonder if I would have found it faster if it had been a Singer. Good chance I would have paged through a service manual one page at a time until I found it. As it was, I had 3 Singer service manuals out just for "ideas".